Historically, telecommunications have involved a transmission of voice and fax signals over a network dedicated to telecommunications, such as the Public Switched Telephone Network (PSTN) or a Private Branch Exchange (PBX). Similarly, data communications between computers have also historically been transmitted on a dedicated data network, such as a Local Area Network (LAN) or a Wide Area Network (WAN).
Currently, telecommunications and data transmissions are being merged into an integrated communication network using technology such as Voice-over internet Protocol (VoIP). Since many LANs and WANs transmit computer data using Internet Protocol (IP), VoIP uses this existing technology to transmit voice and fax signals by converting these signals into digital data and encapsulating the data for transmission over an IP network.
Many VoIP networks employ Class of Service (CoS)/Quality of Service (QoS) distinctions to route traffic through the network. CoS generally refers to partitioning the network traffic into prioritized groups. QoS generally refers to buffering and queuing traffic from endpoint to endpoint, ensuring a particular throughput level. Thus, CoS/QoS is a source-based priority assignment. Callers with a higher CoS/QoS ordinarily receive preferential treatment.